学步园

于3G手机应用视频电话的时候要双camera，那么就存在切换的问题，我就在开发板上进行了调试。marvell的zylonite开发板Windows Mobile6.0 BSP关于camera的驱动变化还是很明显的，采用了wince6.0的camera驱动。
找了半天才在微软的MSDN上看到了各个pdd函数的说明。整个设计的原理就是APP先停止preview，发出切换sensor的指令，驱动响应，把sensor相关的都换成另外一个sensor，然后再重新preview。

首先camera的应用程序得自己写，不然双camera的切换无法在应用上修改，于是找了个camera的应用代码参考了下，居然都编译不过，晕，我不是做app的，但是又没有人帮我，只好硬着头皮看资料看代码。幸好自己也做过一点PC上的应用程序，终于看懂，原来采用WTL+directshow写的camera应用，mainframe+manager+ view+setting结构很清晰。应用程序写上如下代码：

BOOL CCameraManager::CameraSwitchSensor(CAMERA_SWITCH sensor)
 ...{
     LRESULT hr;

     CComPtr<IAMCameraControl> pCameraControl;

     long lCurrentVal,lCurrentFlags;

     long CameraControl_Switch=CameraControl_Flash+0xff;

     if(sensor>=SENSOR_MAX)
         return FALSE;

     CHK(m_pVideoCapFilter->QueryInterface(&pCameraControl));

     CHK(pCameraControl->Get(CameraControl_Switch, &lCurrentVal, &lCurrentFlags));
     if(lCurrentVal == sensor)
     ...{
         //return TRUE;
     }
     CHK(pCameraControl->Set(CameraControl_Switch, sensor, CameraControl_Flags_Manual));

err_exit:
    if( FAILED( hr ))
    ...{
        CCameraParam::GetCameraParam()->GetErrorlog()->WriteLog(L"Error: CCameraManager::CameraSwitchSensor");
        return FALSE;
    }
    return TRUE;
 }

红色字体为关键，由于通过dshow才控制camera，所以得找到dshow动作对应于驱动的接口，参考wm的文档并调试，发现这个可以控制camera，会调用CAM_IOControl，Ioctl=IOCTL_CS_PROPERTY，

EXTERN_C
BOOL
CAM_IOControl(
    DWORD   dwContext,
    DWORD   Ioctl,
    UCHAR * pInBufUnmapped,
    DWORD   InBufLen, 
    UCHAR * pOutBufUnmapped,
    DWORD   OutBufLen,
    DWORD * pdwBytesTransferred
   )
...{
    DEBUGMSG( ZONE_FUNCTION, ( _T("CAM_IOControl(%08x): IOCTL:0x%x, InBuf:0x%x, InBufLen:%d, OutBuf:0x%x, OutBufLen:0x%x) "), dwContext, Ioctl, pInBufUnmapped, InBufLen, pOutBufUnmapped, OutBufLen ) );
    //NKDbgPrintfW(L"CAM_IOControl 0x%x", Ioctl);

    UCHAR * pInBuf = NULL;
    UCHAR * pOutBuf = NULL;
    DWORD dwErr = ERROR_INVALID_PARAMETER;
    BOOL  bRc   = FALSE;
    
    if ( ( NULL == pInBufUnmapped )
         || ( InBufLen < sizeof ( CSPROPERTY ) )
         || ( NULL == pdwBytesTransferred ) )
    ...{
        SetLastError( dwErr );

        return bRc;
    }

    //All buffer accesses need to be protected by try/except
    pInBuf = pInBufUnmapped;

    pOutBuf = pOutBufUnmapped;

    CAMERAOPENHANDLE * pCamOpenHandle = reinterpret_cast<CAMERAOPENHANDLE *>( dwContext );
    CAMERADEVICE     * pCamDevice     = pCamOpenHandle->pCamDevice;
    CSPROPERTY       * pCsProp        = reinterpret_cast<CSPROPERTY *>(pInBuf);
    
    if ( NULL == pCsProp )
    ...{
        DEBUGMSG( ZONE_IOCTL|ZONE_ERROR, (_T("CAM_IOControl(%08x): Invalid Parameter. "), dwContext ) );
        return dwErr;
    }
    
    switch ( Ioctl )
    ...{
        // Power Management Support.
        case IOCTL_POWER_CAPABILITIES:
        case IOCTL_POWER_QUERY:
        case IOCTL_POWER_SET:
        case IOCTL_POWER_GET:
        ...{
            NKDbgPrintfW(L"camera IOCTL_POWER+");

            DEBUGMSG( ZONE_IOCTL, ( _T("CAM_IOControl(%08x): Power Management IOCTL "), dwContext ) );
            __try 
            ...{
                dwErr = pCamDevice->AdapterHandlePowerRequests(Ioctl, pInBuf, InBufLen, pOutBuf, OutBufLen, pdwBytesTransferred );
            }
            __except ( EXCEPTION_EXECUTE_HANDLER )
            ...{
                DEBUGMSG( ZONE_IOCTL, ( _T("CAM_IOControl(%08x):Exception in Power Management IOCTL"), dwContext ) );
            }
            break;
        }

        case IOCTL_CS_PROPERTY:
        ...{
            DEBUGMSG( ZONE_IOCTL, ( _T("CAM_IOControl(%08x): IOCTL_CS_PROPERTY "), dwContext ) );

            __try 
            ...{
                dwErr = pCamDevice->AdapterHandleCustomRequests( pInBuf,InBufLen, pOutBuf, OutBufLen, pdwBytesTransferred );

                if ( ERROR_NOT_SUPPORTED == dwErr )
            ...{
                if ( TRUE == IsEqualGUID( pCsProp->Set, CSPROPSETID_Pin ) )
                    ...{   
                        dwErr = pCamDevice->AdapterHandlePinRequests( pInBuf, InBufLen, pOutBuf, OutBufLen, pdwBytesTransferred );
                    }
                    else if ( TRUE == IsEqualGUID( pCsProp->Set, CSPROPSETID_VERSION ) )
                    ...{
                        dwErr = pCamDevice->AdapterHandleVersion( pOutBuf, OutBufLen, pdwBytesTransferred );
                    }
                    else if ( TRUE == IsEqualGUID( pCsProp->Set, PROPSETID_VIDCAP_VIDEOPROCAMP ) )
                    ...{   
                        dwErr = pCamDevice->AdapterHandleVidProcAmpRequests( pInBuf,InBufLen, pOutBuf, OutBufLen, pdwBytesTransferred );
                    }
                    else if ( TRUE == IsEqualGUID( pCsProp->Set, PROPSETID_VIDCAP_CAMERACONTROL ) )
                    ...{   
                        dwErr = pCamDevice->AdapterHandleCamControlRequests( pInBuf,InBufLen, pOutBuf, OutBufLen, pdwBytesTransferred );
                    }
                else if ( TRUE == IsEqualGUID( pCsProp->Set, PROPSETID_VIDCAP_VIDEOCONTROL ) )
                ...{   
                    dwErr = pCamDevice->AdapterHandleVideoControlRequests( pInBuf,InBufLen, pOutBuf, OutBufLen, pdwBytesTransferred );
                }
                else if ( TRUE == IsEqualGUID( pCsProp->Set, PROPSETID_VIDCAP_DROPPEDFRAMES) )
                ...{   
                    dwErr = pCamDevice->AdapterHandleDroppedFramesRequests( pInBuf,InBufLen, pOutBuf, OutBufLen, pdwBytesTransferred );
                }
                }
            }
            __except ( EXCEPTION_EXECUTE_HANDLER )
            ...{
                DEBUGMSG( ZONE_IOCTL, ( _T("CAM_IOControl(%08x):Exception in IOCTL_CS_PROPERTY"), dwContext ) );
            }

            break;
        }

        default:
        ...{
            DEBUGMSG( ZONE_IOCTL, (_T("CAM_IOControl(%08x): Unsupported IOCTL code %u "), dwContext, Ioctl ) );
            dwErr = ERROR_NOT_SUPPORTED;

            break;
        }
    }
    
    // pass back appropriate response codes
    SetLastError( dwErr );

    return ( ( dwErr == ERROR_SUCCESS ) ? TRUE : FALSE );
}

哈哈，红色字体就是IAMCameraControl的set接口对应于driver会被调用的地方，由于这里还是driver的mdd层，所以尽量不改，于是放到pdd层来实现，很自然的想到AdapterHandleCustomRequests，该函数会调用pdd的DWORD CCameraPdd::HandleAdapterCustomProperties( PUCHAR pInBuf, DWORD  InBufLen, PUCHAR pOutBuf, DWORD  OutBufLen, PDWORD pdwBytesTransferred )，本来这函数是空函数，结果这里就可以放入双camera的切换代码了（不知道是微软写的还是marvell写的，想的真周到，以前还没有的，现在就有了，赞一个），实现如下：

DWORD CCameraPdd::HandleAdapterCustomProperties( PUCHAR pInBuf, DWORD  InBufLen, PUCHAR pOutBuf, DWORD  OutBufLen, PDWORD pdwBytesTransferred )
...{  
    typedef enum
    ...{
        SENSOR_FRONT,
        SENSOR_REAR,
        SENSOR_MAX,
    }CAMERA_SWITCH;   
    
    CONST LONG CAMERACONTROL_SWITCH = CSPROPERTY_CAMERACONTROL_FLASH+0XFF;    
    PCSPROPERTY_CAMERACONTROL_S pCsPropCamControlInput  = NULL;
    CSPROPERTY       * pCsProp = reinterpret_cast<CSPROPERTY *>(pInBuf);
    
   
   
    if( ( TRUE == IsEqualGUID( pCsProp->Set, PROPSETID_VIDCAP_CAMERACONTROL ) ) 
        && (pCsProp->Id == CAMERACONTROL_SWITCH))        
    ...{
        pCsPropCamControlInput = reinterpret_cast<PCSPROPERTY_CAMERACONTROL_S>(pInBuf);
        switch(pCsProp->Flags)